producing new cells 2.1 Flashcards
what are chromosomes
threadlike structures composed of DNA
where are chromosomes found
in the nucleus of plant, animal and fungal cells
how many chromosomes does every cell in our body’s have
46 chromosomes
23 pairs
what is in the structure of chromosomes
centromere and chromotid
why is mistosis/cell division important
for growth, repair and to maintain the diploid chromosome complement
stage 1 of mitosis
starts with a diploid parent cell. the nucleus containing long uncoiled chromosomes become visible under a microscope
stage 2 of mitosis
chromosomes shorten and duplicate. chromosomes now consist of two identical chromatids
stage 3 of mitosis
the nuclear membrane disintegrates and spindle fibres appear. the chromosomes line up at the equator of the cell
stage 4 of mitosis
the spindle fibres contract, separating sister chromatids and pulling them to opposite poles of the cell
stage 5 of mitosis
the cytoplasm divides and 2 new nuclear membranes form around each group of chromotids
stage 6 of mitosis
two new daughter cells form, each with the same number of chromosomes as the parent cell
diploid
a cell that has two matching sets of chromosomes
examples of diploid cells
skin cells and zygote
chromosome complement
the total number of chromosomes present in every cell of a species
haploid
a cell that has a single set of chromosomes
examples of haploid cells
sperm cells and egg cells
chromotids
a single strand of a chromosome, which is replicated before mitosis
stem cells are…
unspecialised cells
what can stem cells do
reproduce themselves indefinitely by repeated mitosis and develop into various types of specialised cells
types of stem cells
embryonic stem cell and adult tissue stem cell
embryonic stem cells
- taken from early developing embryo
- can develop into any cell type found in the body
tissue stem cells
- taken from tissues of an adult (brain, bone marrow and skin)
- can only differentiate into a specialised cell of the same tissue it was taken from
why are stem cells important
for growth and repair
what are specialised cells
cells which have adapted to preform a specific job
organisation of the body
cells->tissues->organs->systems
red blood cell structure
- biconcave disc
- no nucleus
- very small and flexible to be able to fit into capillaries
red blood cell function
to transport oxygen around the body
sperm cell structure
- has a tail to help it swim to the egg
- has many mitochondria so it has lots of energy to swim to the egg
sperm cell function
to swim and fertilise the egg cell
